Japanese Patent No. 4265601 as listed below describes in claim 1, as a technique of controlling a motor of a compressor such as in an air conditioner, “the control unit, upon receiving a stop instruction, detects the rotation speed of the motor in operation by the speed detector and decelerates the motor, by the speed changing ratio changer, to a stopping speed at which an amount of torque control by an inverter is equal to or larger than a predetermined value, and then stops the motor at a rotor position specified by the stop position determiner.”